Magnetic thrust bearings providing axial thrust have recently been developed to replace mechanical thrust bearings used in all types of rotating machines, e.g., turbines, motors and generators, having a rotor and a stator. These magnetic thrust bearings serve to enhance dynamic performance, reduce power loss and possibly reduce the overall length of the associated rotating machine. A typical mechanical thrust bearing and its collar are shown in FIG. 1A which is a schematic cross sectional view of a rotating machine. In FIG. 1A, a conventional stator 10 and a rotor 12 are separated by an air gap 14. As illustrated, rotor 12 includes a projecting thrust collar 16 which rotates with rotor 12 between a fixed thrust stop 18. A typical magnetic thrust bearing is shown in FIG. 1B. As illustrated, the fixed thrust stop of the mechanical thrust bearing of FIG. 1A is replaced by a C-core solenoid coil 19 or by a variation thereof. It will be appreciated that the thrust bearing may be of smaller diameter than the machine rotor diameter and, therefore, may have limited axial force capability. Further, the overall design of the machine may place limits on the axial spacing assigned for the bearing function, thereby additionally restricting overall control.